[Shader] DX12 issue with texture arrays

[Klian]

Summary

After optimizing my materials to reduce drawcalls, a strange shader glitch appeared on my model when I play using DX12, DX11 is fine.

While in dx12: switching to low quality texture fixes the issue. Any quality above is bugged! (See video)

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Assets

Steps to Reproduce

• Create a material based on 3 textures array: Color, Roughness and Normal (pic attached)
• Use an IDMap to assign which index to pick on the model
• Apply and test DX12 / DX11 (Textures Quality > Low)

Expected Result

Clean shader with correct materials

Observed Result

Glitchy shader

Platform(s)

Windows 11 / 3090Ti Latest drivers

Island Code

9311-9744-2560

Upload an image

Video

DX12 Quality Texture Array Bug

[Klian]

Forgot to add one crucial detail:
I’m using 2 UV Maps, one is packed for texture arrays optimization.
The other one is a standard uv map, pretty much a “lightmap” unwrap style, which is used for backed ambient occlusion and metallic maps.

So:
UV0: lightmap style uv, no overlaps, used for global AO and metalness.
UV1: packed with overlapping uvs (IDMap will filter those overlaps) to increase unwrapped surface area. Color, Roughness and Normal are on this UV index.

Cheers

[Klian]

I’ve just double checked and it turns out it’s a compression issue…
Since it’s just a roughness tx i was using linear grayscale as compression setting. Changing it to linear color solves the issue, shouldn’t be the case tho…

Edit: First screenshot has the wrong asset window open (should be texture array instead it’s the source texture), here’s the correct one:

[Bug-Reporter]

FORT-1149769’s status has changed to ‘Ready for QA’. A member of the QA department is investigating the issue.